Glandular tissue at 20x Magnification. Source: Christopher Meade/
Glandular tissue at 20x Magnification. Source: Christopher Meade/

A functional, human ear that is capable of “hearing” out of range radio-frequencies has been created by scientists using a 3D printer and cell culture. Scientists have been able to use tissue engineering combined with 3D printing to make a jaw bone, skin cells for burn treatments, a functional bladder, a model kidney, replacement knee, spine components and even embryonic stem cells that can be used for drug testing or to grow an organ such as a heart.

A team at Wake Forest University reports that they have been able to build “a bioprinter’ that uses cells instead of ink. It even uses an ordinary, off-the-shelf printhead, connected to test tubes full of different cell types instead of wells full of colored inks.” They have also successfully printed bone tissue and a two-chambered mouse heart.  The 3D bones were successfully implanted into mice and using electricity, they were able to shock the heart into beating.

Another group, from a university in Holland is working on a “Skin Print” which ideally will print out sections of human skin to replace damaged skin. Ingmar van Hengel reports that, “With a needle we remove a small piece of healthy skin from the patient. The skin cells are then put in culture where they multiply. The cells serve as ink for the 3D printer and in the hospital a skin grafting can take place with the skin made with a 3D printer/Bioprinter.”

In 3D printing of living tissue, the cells are laid down layer by layer, with a layer of hydrogel in between. The hydrogel acts as a scaffold material. This process is repeated over and over until the desired results are achieved. After the cells have fused, the hydrogel is removed. Then, the tissue is moved to a bioreactor where it continues to grow. 

To create implantable human cartilage, a traditional ink jet printer and an electrospinning machine is used. The Institute of Physics explains, “Combining these systems allowed the scientists to build a structure made from natural and synthetic materials. Synthetic materials ensure the strength of the construct and natural gel materials provide an environment that promotes cell growth.”

"Our approach is consistent with other forms of 3D printing because it's an additive process," says Michael Renard, executive vice president for commercial operations at Organovo" but what is unique is our application of the process in the field of cell biology and tissue engineering."

It will be years before printed organs will be a reality but according to Renard, "In the next 10 years it is possible that [printed] supplemental tissues, ones that aid in regeneration – such as nerve grafts, patches to assist a heart condition, blood vessel segments or cartilage for a degenerating joint – will make it to the clinic. But more advanced replacement tissues will most likely be in 20 years or more."